1. Technical Field of the Invention
The present invention relates in general to the field of communication systems, and in particular, by way of example but not limitation, to reducing signaling traffic with multicasting in a wireless communication network.
2. Description of Related Art
Recent advances in wireless communication technology and associated communication protocols have enabled the development of a wide variety of wireless network configurations capable of operating in a wide variety of wireless environments. As a result, these wireless network configurations have enabled system administrators and network operators to offer voice and data communication services to mobile users that would be difficult or even impossible using convention wireline networks. Wireless Local Area Networks, for example, have enabled organizations to satisfy the communication needs of its increasingly mobile workforce by providing enterprise-wide access to voice and data networks via a wireless interface. Metropolitan Area Networks, on the other hand, have enabled network operators to provide wireless communication services to mobile users located within an entire metropolitan area, and Public Land Mobile Networks further enhance the performance and capabilities of wireless communication services by enabling network operators to cover an even larger geographic region.
Each of these wireless network configurations typically employ a common functional architecture based upon a conventional cellular structure. More particularly, these wireless networks typically divide the wireless coverage area into a number of smaller geographic regions, called cells, where each cell includes a base station for communicating with wireless communication devices located within the base station""s assigned cell. The base stations further communicate with a mobile switching center which acts as an interface between the base stations and backbone networks, such as the Public Switched Telephone Network, the Integrated Services Digital Network and other nodes within the wireless network. The mobile switching center also plays a critical role in coordinating call connection and radio resource management functionalities between the mobile switching center and base stations located within the mobile switching center""s Service Area. In this context, the mobile switching center is responsible for coordinating call set-up, call supervision and call release. The mobile switching center is also responsible for communicating signaling information to the base stations that coordinate, for example, paging of a target wireless communication device in response to an incoming call and in some implementations, handover of a wireless communication device between base stations located within the mobile switching center""s Service Area.
One significant problem associated with these types of wireless networks is that the mobile switching center typically communicates signaling information to the base stations using a unicast communication scheme. This communication scheme requires that signaling information be communicated to each base station in a separate communication using each base station""s associated network or host address. Although this communication scheme performs adequately for discrete communications between the mobile switching center and a single base station, the communication scheme becomes inefficient in situations where the mobile switching center must communicate the same signaling information to a relatively large group of base stations. For example, when the mobile switching center receives an incoming call addressed to a target wireless communication device, the mobile switching center must address a separate paging command to each base station located within a Location Area, which is typically the Location Area with which the target wireless communication device last performed a registration or location update procedure. If the Location Area includes, for example, three base stations, the mobile switching center must replicate the paging command and communicate a corresponding one of three replicated paging commands to the three base stations, even if the three paging commands traverse the same communication links between the mobile switching center and each of the three base stations. As a result, this communication scheme proves to be not only time-consuming, but also wastes precious processing resources of the mobile switching center that could be used to perform other tasks and increases the signaling load over the communication links between the mobile switching center and the base stations.
Therefore, in light of the deficiencies of existing communication schemes, there is a need for a mechanism that reduces signaling traffic communicated from a mobile switching center to a plurality of base stations.
The deficiencies of the prior art are overcome by the method, system and apparatus of the present invention. For example, as heretofore unrecognized, it would be beneficial to reduce signaling traffic communicated from a mobile switching center to a plurality of base stations by associating the plurality of base stations to form one or more multicast groups and by assigning a multicast group address to each multicast group for use in subsequent multicast communications to the plurality of base stations within each multicast group. A network interface associated with each of the plurality of base stations within each multicast group may be configured to filter signaling traffic for signaling information addressed to the host address associated with the base station and multicast messages addressed to the multicast group to which the base station belongs. The mobile switching center may then communicate signaling information to each-of the plurality of base stations within a multicast group by communicating a single multicast message using the multicast group""s corresponding multicast group address.
If the mobile switching center and the base stations are located on different subnetworks, multicast-enabled routers may be connected between the mobile switching center and the plurality of base stations to ensure that multicast messages are only routed over communication links which include a corresponding multicast group member. These multicast-enabled routers may be configured as separate functional units, or alternatively, one or more network interfaces associated with the plurality of base stations may be configured with multicast-routing functionalities. Another alternative utilizes one or more filter switches which only forward multicast messages over communication links that include a corresponding multicast group member, thereby preventing unnecessary communication of the multicast message over communication links which do not include a corresponding multicast group member.
In one embodiment of the present invention, signaling traffic corresponding to paging commands communicated from the mobile switching center to the base stations located within the mobile switching center""s Service Area is reduced by associating the plurality of base stations to form a multicast group for each Location Area and a separate multicast group for the Service Area. In response to an incoming call addressed to a target wireless communication device, the mobile switching center communicates a first paging command to the host address associated with the base station with which the wireless communication device last updated. If the target wireless communication device does not respond to the first page, the mobile switching center communicates a second paging command addressed to the multicast group associated with the Location Area in which the target wireless communication device last updated. If the target wireless communication device does not respond to the second page, the mobile switching center communicates a third paging command addressed to the multicast group associated with the Service Area.
The technical advantages of the present invention include, but are not limited to, the following exemplary technical advantages. It should be understood that particular embodiments may not involve any, much less all, of the following exemplary technical advantages.
An important technical advantage of the present invention is that it provides a mechanism for efficiently reducing signaling traffic communicated from the mobile switching center to a plurality of base stations.
Another important technical advantage of the present invention is that it enables the mobile switching center to quickly communicate signaling information to a plurality of base stations without requiring repeated communication of the same signaling information to each of the plurality of base stations.
Yet another important technical advantage of the present invention is the ability to reduce the signaling load on communication links between the mobile switching center and the plurality of base stations by enabling a single multicast message to be received by all multicast group members.
Yet another important technical advantage of the present invention is the ability to optimally route signaling information so that signaling information addressed to a multicast group does not traverse communication links that do not connect a corresponding multicast group member.